Developmental regulation of preproenkephalin mRNA in the ovine paraventricular nucleus: effects of stress and glucocorticoids.

摘要: The opioid peptides have profound effects at several levels within the hypothalamo-pituitary-adrenal (HPA) axis. Activation of fetal HPA function occurs during late gestation, and as part adaptive response to stress. Changes in relative levels, localization distribution hypothalamic preproenkephalin (PENK) mRNA ovine paraventricular nucleus (PVN) development were examined by situ hybridization histochemistry. hypoxemia applied presence or absence concomitant cortisol, establish negative feedback potential gestation also investigated. PENK was present low PVN, d60 (term d147). During mid there an increase from d60–80 d100–120, then reaching a peak d130–140. Levels decreased dramatically last 5–7 days prior parturition, but increased again newborn lamb. Throughout confined exclusively parvocellular region PVN. Cortisol infusion induced significant decreases (P < 0.05) mRNA, normoxemic fetuses d135 gestation. hypoxemic insult, which is known stimulate plasma ACTH these fetuses, did not significantly affect mRNA. There no difference between saline cortisol infused fetuses. However, combination compared saline-infused Together, results indicate that elevation endogenous end may act inhibit expression gene PVN developing fetus.